Just a few feet away, though, in the multiplex parking lot, James Holmes was the picture of calm, “just standing there” in a helmet, gas mask and body armor, staring off into the distance.

“He seemed very detached from it all,” Officer Jason Oviatt of the Aurora, Colo., Police Department testified Monday as a preliminary hearing got under way with graphic testimony about the July 20 carnage at a midnight screening of a Batman movie.

“Very, very relaxed.”

Oviatt was the first witness at a hearing that saw a veteran officer break down on the stand as he described finding the body of a 6-year-old girl – one of 12 people killed and 58 wounded in the ambush.

Victims’ relatives sat quietly in the courtroom as officers recalled how one wounded woman stopped breathing every time she was moved, another victim gasped for breath on the way to the hospital, a third kept asking if his wife would live.

One cop spoke of a sound that will probably haunt him forever: the slosh of blood in the back seat of the car he used to take six people from the Century 16 cinema to the hospital.

Through all the gut-wrenching testimony – which included the revelation that Holmes, 25, bought his ticket to the movie 12 days before the screening – the bearded massacre suspect did not react.

His demeanor was apparently not that different from the one Oviatt encountered in the parking lot last summer.

Oviatt was on the graveyard shift in the Denver suburb when the call about the shooting came in. He followed a trail of blood to the back of the building and found Holmes standing by a car in SWAT-type gear.

He thought he was a police officer, but as he got closer, realized he was wrong.

At gunpoint, he ordered the suspect to put up his hands and get on the ground, where he handcuffed him. Holmes – dripping with sweat, his pupils wildly dilated, reeking of body odor – did not display “normal emotional responses” and did not resist, he said.

The officers asked him if he was alone and Holmes responded with a strange smile, “like a smirk,” Officer Justin Grizzle testified.

There was a rifle by the car, and when Oviatt searched Holmes, he found two ammunition magazines in his pocket and two knives. Holmes volunteered that his home had been booby-trapped with “improvised explosive devices,” Oviatt said.

Officer Aaron Blue helped Oviatt search Holmes, but after the suspect was secure, his attention was drawn to the theater, where another cop was pulling out a woman who had been shot in the head and the leg.

The woman was Jessica Ghawi, 24, a blogger who had been tweeting about the movie, “The Dark Knight Rises,” not long before Holmes allegedly tossed tear-gas canisters into the theater and opened fire.

Blue and the other officer took her to University Hospital, where she died.

Grizzle went into the theater, where he heard people screaming and stepped over an assault rifle left on the blood-slicked floor. Alarms were going off and “The Dark Knight Rises” was still playing on the screen. All around him, he saw still bodies and “some gunshot victims that were just crawling to get out."

He made four trips to the hospital with victims.

“I didn’t want anyone else to die,” he said.

On his first drive, Ashley Moser, 25, shot in the head and abdomen, was in the back seat. Her boyfriend kept asking, “That’s my wife. Is my wife going to live?” and tried to jump out of the car to find Ashley’s 6-year-daughter. The pregnant mom survived but later miscarried and was paralyzed. Her daughter, Veronica, died.

On another trip, standup comic Caleb Medley was in the back seat. He’d been shot in the face and was making terrible noises. Each time he stopped breathing, the officer, using an expletive, ordered him not to die. Medley survived.

By the time Grizzle was done transporting the wounded, he noticed his patrol car was spattered with blood.